无机柱撑蒙脱石的微波制备及吸附作用研究

用微波加热方法制备无机柱撑蒙脱石，并用X射线衍射分析法对其结构进行表征；研究了未改性蒙脱石和无机柱撑蒙脱石吸附水溶液中F^-离子的适宜条件及吸附模式。结果表明，无机柱撑蒙脱石的层间距增加为1．7395nm；室温条件下，F^-离子初始质量浓度50mg／L，吸附剂投加量20g／L,吸附振荡时间为40min时，无机柱撑蒙脱石对F^-的去除率达74．6％，较相同条件下未改性柱撑蒙脱石对F^-离子的去除率提高了19．5％；吸附等温线符合Freundlich吸附等温方程。     

铝柱撑膨润土对甲基橙的吸附性能研究

以铝的多聚羟基阳离子为柱撑剂对天然钠基膨润土进行柱撑改性,制备铝柱撑膨润土,并以其为吸附剂,通过静态吸附实验考察了其对废水中甲基橙的吸附性能。结果表明,膨润土经过铝柱撑改性后,其吸附性能得到了较大的提高。甲基橙在铝柱撑膨润土上的吸附过程可以通过伪一级动力学方程和Langmuir吸附等温线来描述。     

二氧化钛柱撑膨润土对染料甲基橙的吸附行为

以sol-gel法制备TiO2溶胶和钇掺杂TiO2溶胶为柱化剂,制备出了TiO2柱撑膨润土和钇掺杂TiO2柱撑膨润土.X射线衍射分析表明经柱撑后的膨润土层间距明显增大,达1.9 nm以上,经500℃煅烧后其层间距稳定在1.8 nm以上.研究了甲基橙在4种TiO2柱撑膨润土上的吸附行为,结果表明4种TiO2柱撑膨润土吸附染料甲基橙的速率和吸附量均较大,其吸附动力学行为均遵循Bangham方程和Langmuir方程所描述的规律.平衡吸附量qe与平衡浓度ρe之间的关系符合Freundlich和Langmuir等温吸附方程.其吸附均为吸热过程,吸附热值在12～17kJ/mol,吸附表现为表面物理吸附和离子交换作用.     

TiO2改性柱撑膨润土吸附副品红的性能研究

以钠基膨润土为原料,制备了4种二氧化钛(TiO2)改性柱撑膨润土,并探讨了膨润土的改性方法、投土量、溶液的振荡时间、温度、pH值等因素对膨润土吸附副品红实验的影响.结果表明,4种TiO2改性柱撑膨润土对副品红的吸附效果明显好于原土;未经煅烧的TiO2改性柱撑膨润土的吸附效果要明显优于经高温(500 ℃)煅烧过的柱撑膨润土;掺杂钇的TiO2改性柱撑膨润土的吸附性能略好于未经掺杂的柱撑膨润土;膨润土投土量、溶液的振荡时间、温度和pH值均会对柱撑膨润土的吸附效果产生影响;20 ℃时,4种柱撑膨润土对溶液中副品红的吸附等温线均符合Langmuir吸附等温方程.     

铝柱撑改性膨润土处理电镀废水中Cr6+的实验研究

以膨润土为原料制备了铝柱撑改性膨润土,并研究了不同影响因素对铝柱撑改性膨润土去除电镀废水中Cr6+的影响.结果表明:铝柱撑改性膨润土对Cr6+的去除率明显优于膨润土原土;废水的pH、吸附时间和膨润土投加量对Cr6+的去除率影响较大;pH＝4,吸附时间为40 min,投加质量浓度为40 g/L,铝柱撑改性膨润土对Cr6+的去除率达到最大86.1％;铝柱撑改性膨润土对电镀废水中Cr6+的吸附符合Langmuir吸附等温方程.     

羟基铁柱撑蒙脱石对庆大霉素的吸附性能

以蒙脱石K10为原料,制备出OH/Fe摩尔比分别为0.6、0.8、1.0、1.5和2.0的系列羟基铁柱撑蒙脱石吸附剂(OH/Fe蒙脱石),比较它们对庆大霉素的吸附能力,研究pH值和时间等因素对OH/Fe蒙脱石吸附庆大霉素的影响规律,并分析吸附机理。结果表明:柱撑OH/Fe蒙脱石对庆大霉素吸附量从低到高依次为K10(33.3 mg/g)、0.6 OH/Fe(43.4 mg/g)、0.8 OH/Fe(44.8 mg/g)、1.0 OH/Fe(56.0 mg/g)、2.0 OH/Fe(64.8 mg/g)、1.5 OH/Fe(71.9 mg/g),OH/Fe摩尔比为1.5时吸附量最大,达到K10的2倍以上,符合Freundlich吸附等温线。柱撑蒙脱石对庆大霉素的吸附在3 h内接近吸附平衡,并且吸附量随pH值的增加而显著增加,吸附可用伪二阶动力学方程描述。吸附量增大主要归功于柱撑后蒙脱石层间距增大,阳离子交换是庆大霉素进入蒙脱石的主导机制,表面配位的化学吸附也是另一种辅助机制,同时羟基铁柱撑蒙脱石吸附庆大霉素后柱撑结构易坍塌。     

TiO2柱撑膨润土对染料茜素黄的吸附行为

以Sol—Gel法制备TiO_2溶胶和钇掺杂TiO_2溶胶为柱化剂,制备出了TiO_2柱撑膨润土和钇掺杂TiO_2柱撑膨润土;X射线衍射分析表明,经柱撑后的膨润土层问距明显增大,达1.9nm以上,经500℃煅烧后其层间距稳定在1.8nm以上。研究了茜素黄在4种TiO_2柱撑膨润土上的吸附行为,结果表明:4种TiO_2柱撑膨润土吸附染料茜素黄的速率和吸附量均较大,其吸附动力学行为均遵循Bangham方程和Langmuir方程所描述的规律。平衡吸附量q_e与平衡浓度p_e之间的关系符合Freundich和Langmuir等温吸附方程。其吸附均为吸热过程,吸附热值在13kJ.mol~(-1)～16kJ.mol~(-1)范围,吸附表现为表面物理吸附和离子交换作用。     

蒙脱石和高岭石吸附水溶液中重金属离子的实验研究

综述了近几年研究人员以蒙脱石、高岭石和膨润土作为吸附材料,去除水溶液中的砷、镉、铬、铜、铅几种重金属离子。通过酸性活化改性,有机分子嫁接改性,纳米氧化物涂层和柱撑等手段,提高了粘土矿物的吸附性能,达到更好的吸附效果。结果表明有机改性更有利于蒙脱石等粘土矿物对于重金属离子的吸附,同时指出pH是影响吸附效果的关键因素。     

锆柱撑蒙脱石对黄药的吸附机理EI北大核心CSCD

以氧氯化锆为锆源,将聚合羟基阳离子Zr^(4+)柱撑插入提纯钠化蒙脱石(Na-mt)层间制备锆柱撑蒙脱石(Zr-Pmtn)材料。用X射线衍射、Fourier变换红外光谱和热重-差热分析对样品进行表征,并测定了Zr-Pmtn材料对废水中黄药的吸附效果。结果表明:Zr-Pmtn材料的晶面间距为1.99 nm,热稳定性较好,具有良好的吸附性能;吸附时间为90 min时,吸附动力学达到平衡,溶液最佳pH=3,Zr-Pmtn材料对黄药的饱和吸附量为5.75 mg/g,且Zr-Pmtn材料对黄药的吸附动力学符合拟二级动力学方程,吸附平衡数据符合Langmuir等温线模型。Zr-Pmtn材料吸附黄药属于自发过程和吸热反应。     

Fe-Al柱撑膨润土吸附染料酸性大红的性能

制备了Fe-Al柱撑膨润土,研究了其对染料酸性大红的吸附去除性能,结果表明:Fe-Al柱撑膨润土对染料酸性大红有很好的去除效果,当其用量为0.1g时,染料酸性大红的吸附去除率达到92.6%;Fe-Al柱撑膨润土对染料酸性大红的吸附在60分钟达到平衡;pH值对染料酸性大红的去除有一定的影响,在酸性和碱性条件下的去除率大于中性。平衡吸附量qe与平衡质量浓度pe之间的关系符合Freundlich和Langmuir等温吸附方程所描述的规律。     

有机改性蒙脱土对农药敌草隆的吸附研究

以十六烷基三甲基溴化铵(CTAB)有机改性蒙脱土为吸附剂,采用静态摇瓶试验,研究了改性蒙脱土对除草剂敌草隆的吸附行为.探讨了温度、离子强度、腐殖酸、溶液pH值对敌草隆吸附的影响.试验结果表明,CTAB改性蒙脱土对敌草隆具有较大的吸附容量,最大吸附量为20.31 mg/g吸附等温线可用Freundllich方程来描述;吸...     

氯化锌造孔壳炭对Cr(Ⅵ)的吸附研究

采用氯化锌浸渍活化法制备了氯化锌造孔壳炭,研究了其对废水中Cr(Ⅵ)的吸附效果,并采用SEM、FTIR和BET等方法对改性壳炭的结构进行了表征。结果表明,处理初始Cr(Ⅵ)质量浓度为20 mg/L的水样,当温度为25℃,改性壳炭投加量为0.5 g,pH为2.0,吸附时间为180 min时,Cr(Ⅵ)去除率为98.8%,最大Cr(Ⅵ)吸附量为11.284 mg/g。拟合结果显示,Langmuir等温吸附方程可以较好地拟合改性壳炭对Cr(Ⅵ)的吸附过程,该动态吸附平衡遵循拟二级动力学方程。     

MnO2负载蒙脱土对溴百里香酚蓝的脱色研究

研究了MnO2负载蒙脱土对溴百里香酚蓝的吸附脱色性能，绻果表明：蒙脱土可以改善MnO2在吸附过程中的分散性，提高吸附能力。试验表明该吸附过程符合Lagergren二级速率动力学方程，当MnO2负载蒙脱土用量为1．0g，pH较低，质量浓度10～50mg／L时，较短时间内就仃很好的脱色效果，脱色率可达96．44％。     

Arsenic adsorption mechanism on clay minerals and its dependence on temperature

In the present study, the As(V) removal efficiency of different clay minerals was investigated as a function of solution pH, time, As(V) concentration, and temperature. Arsenic mobility was also investigated by determining the As(V) released from the loaded samples by leaching with various aqueous solutions. The kinetics of adsorption was observed to be fast and reached equilibrium within 3 h. As(V) adsorption on studied clays was pH dependent and maximum adsorption was achieved at pH 5.0. The maximum adsorption capacity was calculated by fitting the Langmuir equation to the adsorption isotherms and found to be 0.86, 0.64, and 0.52 mg As(V)/g of kaolinite, montmorillonite, and illite, respectively. The negative effect of temperature on As(V) adsorption showed the interactions to be exothermic. Based on the results, it was found that among the studied clay minerals, kaolinite was the best As(V) adsorbent and montmorillonite had strong retention capacity. The electrokinetic behavior of kaolinite and montmorillonite was modified in the presence of As(V), indicating that adsorption involves inner sphere surface complexation and strong specific ion adsorption.     

Removal of Basic Dye Crystal Violet from Aqueous Solution by Cu(II)-Loaded Montmorillonite

The effects of contact time, reaction temperature, and ionic strength on crystal violet adsorption onto Cu(II)-loaded montmorillonite were studied. The kinetic experimental data were analyzed using pseudo-first-order, pseudo-second-order, and Elovich equations to examine the adsorption mechanism. The result suggested that the adsorption was best represented by the pseudo-second-order equation. The suitability of the Langmuir, Freundich, and Temkin isotherms to equilibrium data was also investigated at 25°C. The maximum adsorption capacity was 114.3 mg dye/g Cu(II)-loaded montmorillonite at adsorbent concentration 1 g/L. The differential heat of adsorption was evaluated and the result showed that adsorption of crystal violet onto the Cu-loaded sample was chemical in nature. The ionic strength and reaction temperature exhibited an insignificant impact on the crystal violet adsorption. The Cu(II)-loaded montmorillonite could serve as low-cost adsorbents for removing crystal violet from aqueous solution compared to the data reported in the literature.     

Arsenic adsorption on Ti‐pillared montmorillonite

BACKGROUND: Arsenic pollution in drinking water has been found in most countries. Arsenate (As(V)) and arsenite (As(III)) are two major forms of inorganic arsenic species, and the latter is the more toxic. The removal of arsenic ions from water has attracted increased attention, and therefore further understanding and development of techniques for removal of arsenic ions are required. RESULTS: Adsorption of arsenate and arsenite from aqueous solutions using Ti‐pillared montmorillonite (Ti‐MMT) was investigated as a function of contact time, pH, temperature, coexisting ions, and ionic strength. The adsorption of both arsenate and arsenite were temperature and pH dependent, indicating different adsorption mechanisms. The effect of coexisting ions on the adsorption was also studied and, among the ions investigated, only phosphate had a noticeable influence on the adsorption of arsenate, while the effect of other ions was negligible. A pseudo‐second‐order chemical reaction model was obtained for both arsenate and arsenite; adsorption isotherms of arsenate and arsenite fitted the Langmuir and Freundlich isotherm models well. X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) were used to study the nature of surface elements before and after adsorption. CONCLUSIONS: This work demonstrates that Ti‐pillared montmorillonite is an efficient material for the removal of arsenate and arsenite from aqueous solutions. Experimental parameters such as contact time, solution pH, temperature, initial concentration, coexisting ions, and ionic strength have been optimized. Copyright © 2010 Society of Chemical Industry     

Novel batch reactor design for the adsorption of arsenate on chitosan

BACKGROUND: The sorption of arsenate, a poison of acute toxicity found in natural waters, onto chitosan, a biosorbent derived from waste seafood shells has been studied. A batch adsorber design model was developed to determine how much chitosan adsorbent is required to reduce the arsenate concentration in solutions to the WHO standard of 10 µg L^?1. RESULTS: A series of batch kinetic experiments has been carried out at different initial pH values. The initial arsenate sorption appears to be completed after 30 min, however, a steady reversible reaction takes place resulting in the desorption of arsenate over 48 h. These phenomena in the batch kinetic data have been correlated simultaneously using the newly developed pseudo‐first order reversible model. Two batch reactor design models have been developed and compared. The first model is a conventional approach based on the equilibrium isotherm capacity equation. A second batch adsorption reactor design is based on the principle of contacting time required, t_max, for the chitosan to achieve its maximum adsorption capacity, q_max. The practical outcome from the second batch adsorber model results in a saving in adsorbent mass per batch of approximately 39.4%, 96.2% and 92.3% chitosan adsorbent at pH conditions of 3.5, 4.0 and 5.0, respectively. CONCLUSION: The adsorbent cost and handling costs are reduced in the second batch adsorber model. There is also a significant savings in the batch turnaround time required in the batch adsorber design when the design is based on the maximum adsorption capacity rather than the equilibrium adsorption capacity. Copyright © 2010 Society of Chemical Industry     

Oxidized and Ethylenediamine-Functionalized Multi-Walled Carbon Nanotubes for the Separation of Low Concentration Arsenate from Water

In this work multiwalled carbon nanotubes (MWCNTs) modified by oxidation (o-MWCNTs) and by aminofunctionalization (e-MWCNTs) were examined as potential adsorbents for arsenate removal from water. Adsorption characteristics of raw and modified MWCNTs were investigated in batch adsorption experiments. The influence of solution pH (pH range 3–10), contact time, and temperature (25, 35, and 45°C) were studied. Ethylenediamine-functionalized MWCNTs have the greatest affinity for arsenate ions, followed by o-MWCNTs and raw-MWCNTs. The obtained experimental data for raw- and o-MWCNTs fitted Sips isotherm model, while for the e-MWCNTs, the Freundlich model provided the best fit to the experimental points. The maximum adsorption capacity for arsenate ions was achieved using e-MWCNTs, 12.18 mg g^?1. The presence of the arsenate on the adsorbent is confirmed by FTIR spectroscopy. Thermodynamic studies indicated the spontaneity and endothermic nature of the adsorption. Sodium hydroxide solution (0.1 M) was found to desorb about 70% of arsenate from e-MWCNTs. The results with spiked drinking water samples demonstrated that e-MWCNTs, due to the present basic and acidic groups, were very efficient for the removal of arsenate ions, as well as of some cations, at pH 4.     

改性玉米秸秆对Cu2+吸附性能研究

研究了NaOH、HNO3改性玉米秸秆对水中Cu^2+的吸附性能及吸附特性。研究表明,改性后的秸秆表面光滑,结晶指数高,对Cu^2+的吸附容量增大。相比未改性玉米秸秆和酸改性玉米秸秆,碱改性玉米秸秆对Cu^2+的吸附效果最好。碱改性玉米秸秆对Cu^2+的吸附能较好地符合Freundlich方程和伪二级动力学模型。初步推断吸附机理是秸秆表面官能团与Cu^2+络合形成复合体的化学吸附过程。     

聚合铝蒙脱土的制备及其吸附染料性能

采用聚合硫酸铝对蒙脱土进行改性,比较钠基蒙脱土和改性蒙脱土对染料的吸附性能,得到两种吸附剂的加入量对染料去除率的影响、吸附动力学曲线、等温吸附曲线.结果表明改性蒙脱土的吸附能力远远大于钠基蒙脱土.